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Kees Cook 2edd8c192f net/mlx4_en: Introduce flexible array to silence overflow warning 
[ Upstream commit f8f185e39b ]

The call "skb_copy_from_linear_data(skb, inl + 1, spc)" triggers a FORTIFY
memcpy() warning on ppc64 platform:

In function ‘fortify_memcpy_chk’,
    inlined from ‘skb_copy_from_linear_data’ at ./include/linux/skbuff.h:4029:2,
    inlined from ‘build_inline_wqe’ at drivers/net/ethernet/mellanox/mlx4/en_tx.c:722:4,
    inlined from ‘mlx4_en_xmit’ at drivers/net/ethernet/mellanox/mlx4/en_tx.c:1066:3:
./include/linux/fortify-string.h:513:25: error: call to ‘__write_overflow_field’ declared with
attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()?
[-Werror=attribute-warning]
  513 |                         __write_overflow_field(p_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Same behaviour on x86 you can get if you use "__always_inline" instead of
"inline" for skb_copy_from_linear_data() in skbuff.h

The call here copies data into inlined tx destricptor, which has 104
bytes (MAX_INLINE) space for data payload. In this case "spc" is known
in compile-time but the destination is used with hidden knowledge
(real structure of destination is different from that the compiler
can see). That cause the fortify warning because compiler can check
bounds, but the real bounds are different.  "spc" can't be bigger than
64 bytes (MLX4_INLINE_ALIGN), so the data can always fit into inlined
tx descriptor. The fact that "inl" points into inlined tx descriptor is
determined earlier in mlx4_en_xmit().

Avoid confusing the compiler with "inl + 1" constructions to get to past
the inl header by introducing a flexible array "data" to the struct so
that the compiler can see that we are not dealing with an array of inl
structs, but rather, arbitrary data following the structure. There are
no changes to the structure layout reported by pahole, and the resulting
machine code is actually smaller.

Reported-by: Josef Oskera <joskera@redhat.com>
Link: https://lore.kernel.org/lkml/20230217094541.2362873-1-joskera@redhat.com
Fixes: f68f2ff915 ("fortify: Detect struct member overflows in memcpy() at compile-time")
Cc: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/20230218183842.never.954-kees@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-03-10 09:33:08 +01:00
arch LoongArch, bpf: Use 4 instructions for function address in JIT 2023-03-10 09:33:06 +01:00
block block: use proper return value from bio_failfast() 2023-03-10 09:32:47 +01:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: rsa-pkcs1pad - Use akcipher_request_complete 2023-03-10 09:33:03 +01:00
Documentation attr: use consistent sgid stripping checks 2023-03-03 11:52:25 +01:00
drivers net/mlx4_en: Introduce flexible array to silence overflow warning 2023-03-10 09:33:08 +01:00
fs erofs: relinquish volume with mutex held 2023-03-10 09:32:46 +01:00
include net/mlx4_en: Introduce flexible array to silence overflow warning 2023-03-10 09:33:08 +01:00
init gcc: disable -Warray-bounds for gcc-11 too 2023-01-14 10:33:43 +01:00
io_uring use less confusing names for iov_iter direction initializers 2023-02-09 11:28:04 +01:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel bpf: Fix global subprog context argument resolution logic 2023-03-10 09:33:06 +01:00
lib lib/mpi: Fix buffer overrun when SG is too long 2023-03-10 09:32:52 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm/gup: add folio to list when folio_isolate_lru() succeed 2023-02-22 12:59:54 +01:00
net l2tp: Avoid possible recursive deadlock in l2tp_tunnel_register() 2023-03-10 09:33:07 +01:00
rust rust: print: avoid evaluating arguments in pr_* macros in unsafe blocks 2023-02-06 08:06:34 +01:00
samples ftrace: Export ftrace_free_filter() to modules 2023-02-01 08:34:37 +01:00
scripts scripts/tags.sh: fix incompatibility with PCRE2 2023-03-03 11:52:25 +01:00
security randstruct: disable Clang 15 support 2023-02-25 11:25:43 +01:00
sound ASoC: codecs: es8326: Fix DTS properties reading 2023-03-03 11:52:22 +01:00
tools selftests/net: Interpret UDP_GRO cmsg data as an int value 2023-03-10 09:33:07 +01:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: Fix potential deadlock on vfio group_lock 2023-02-01 08:34:36 +01:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS audit: update the mailing list in MAINTAINERS 2023-02-25 11:25:42 +01:00
Makefile Linux 6.1.15 2023-03-03 11:52:25 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.